Alvah wiswall



A. WISWALL.

ELECTRO MAGNETIC ALARM.

(No Mqdel.)

Patented Oct. 16, 1883.l

. Erin-IV #WWW/ UNITED STATES PATENT OEEICE.

ALV AH VISVALL, OF CINCINNATI, OHIO, ASSIGNOR, BY DIRECT AND MESNEASSIGNMENTS, TO FREDERICK VOELCKEL, OF SAME PLACE.

ELECTRO-MAGNETIC ALARM.

SPECIFICATION forming part of Letters Patent No. 286,888, dated October16, 1883.

(No model.)

.To all whom t may concern:

Be it known that I, ALvAII VIswALL, of Cincinnati, Hamilton county,Ohio, have invented a new and useful Improvement in Electro-MagneticAlarms, of which the following is a specification.'

My invention relates to the class of devices in which the act ofalighting or walking across a particular spot is made known at adist-ant station by an electro-magnetic alarm.

Using any of the well-known electro-mag netic alarms and the ordinarymeans of electrical comiminication, my invention is direct ed to a novelmechanical device whereby the I 5. pressure of the passers foot is madeeffective to close or to open the circuit, according to whether anormally-open or normally-closed circuit is employed. This mechanicaldevice consists, essentially, of an india-rubber tube, 2O at one or bothends of which is an expansible sac or bladder, whose inflation by theair driven into it by the pressure of the intruders foot causes contactof the wire terminals, so as to complete the circuit, and by so doingbring 2 5 into activity the alarm by any of the familiar modes.

In thc accompanying drawings, Figure l is a ground plan of a premisesprovided with my improvement. Figs. 2 and 3 are longitudinal 3o sectionsof the circuit-maker in its open and closed conditions, respectively.Figs. 4 and 5 are end views of the device shown in Figs. 2 and 3,respectively. Figs. 6 and 7 are longitudinal and transverse sections,respectively,

g, 5 of a modification of my circuit-maker.

A may represent an apartment protected by my device. B B B representindia-rubber tubing, preferably closed at one end. The other end of thetubing enters a sac or bladder, C,

4o of india-rubber, oil-silk, or any other suitable flexible imperviousmaterial. Likewise secured to said tube end -is a metallic sheath, D,

whichis in electrical communication with one of the battery-wires E.Also secured to tube B, but insulated from vthe sheath D, is a metallicspring, F, whose resilience (except when said spring is pressed forciblyoutward) maintains it out of contact with the sheath D. Compression nponthe tubing B (such as would be made by the foot of a person passing overit) 5o forces air into the sac C, which, expanding the latter, causes itto force the spring F outward, so as to bring it in contact with thesheath D, and by thus completing the circuit to sound the distant alarm.

Various forms of circuit-closers may, obviously, be combined with suchtubing and sac. For example, a form may be given to the spring such asshown in Figs. 6 and 7, which show such a form in its closed condition.

The tubing E may be made to assume the undulating form shown or a coiledor other arrangement by a fastening of twine or netting, canvas, orother flexible fabric, or it may remain unattached and be simply laidunderneath a carpet or rug or other floor-covering.

vWhen employed in connection with a closed circuit, all the systems oftubing may, if desired, be united in one series, so as to save wire. l

' I claim as new and of my inventionw In an electric burglar-alarm, theflexible airtube B, forming a mat, in combination with an expansiblesacconnected thereto, and a eircuit closer or opener havingcontact-pieces, the 75 sac to act on one of the contact-pieces, as setforth.

In testimony of which invention I hereunto set my hand. Y

ALVA H VISWALL.

Attest:

GEO. H. KNIGHT, SAME. S. CARPENTER.

